24 October 2014
Sign up to our newsletterWant more news like this? Sign up to our newsletter.


A large wind tunnel fan which uses RotaBolt measurement fasteners to secure its main rotor blades to a central hub has clocked up nearly 30 years of trouble-free service at an automotive vehicle testing centre in Russia.

The fan was constructed in 1984 and entered full service in 1986 but it wasn't until this year that the centre re-contacted James Walker RotaBolt to enquire about specialist lubrication greases, and to also report that the fasteners were still operating trouble-free in monitoring and maintaining the correct bolt load.

The fan has a rotor diameter of 7.5 metres and operates at a speed of 350 RPM in a closed metal channel, creating an airflow of 55 m/s. There are eight blades which are 3 metres long and are each fastened to the main hub by ten M24 x 3.0 x 100mm RotaBolts which were installed with a pre-set load of 22 tonnes.

The original specification of using RotaBolts over 30 years ago was made by the company that constructed the hand-crafted wooden blades – Permali Gloucester Ltd. Although they no longer manufacture these blades, they were able to confirm the original design parameters and detail of the fan's construction.

Wind tunnel fan blades were generally constructed from laminations of selected spruce and birch woods. The aerofoil shape of the blades was hand crafted and each blade was attached into a forged machined steel adaptor using a custom tapered threaded root. The blades were then attached to the hub using the RotaBolts.

The use of an adaptor allowed the blade pitch to be adjusted to alter the flow in the tunnel, unlike the fixed pitch blades which were simply sandwiched between two hub plates.

The main characteristics of laminated wood blade construction are high structural integrity and resilience to operating stresses. Another key benefit is the freedom from fatigue – a quality also found in bolted joints that use RotaBolt measurement technology to successfully achieve and maintain the correct tension throughout their 30 year life.

Paul Gay

Related Websites


Related Companies

James Walker RotaBolt Ltd

Similar Articles

Design, Online – A Eureka! Web

Eureka! launches 'Design, Online', a new webinar event featuring five leading technology companies.

Wind turbine safety

Global fastener experts Cooper & Turner has provided fastener security for the renewable energy industry for over 25 years, producing bolts and fixings for wind turbine structures ...

Specialist enclosure products

As an increasing number of industries use cabinets, secure boxes and other enclosure units to house electronics, wiring and other systems in public places, there is also a need ...

Custom special fasteners

Sometimes bigger isn’t always better, this is especially the case when small batch runs of special or custom solutions are required. These are hard for volume manufacturers to ...

Securing automotive's future

Fasteners are playing a major role in the electric vehicle revolution.

Easy tensioning of large bolts

Tensioning of large bolted joints usually requires the use of electric, hydraulic or pneumatic tools, a factor that can add costs and delays to any project. But not anymore.


Bollhoff’s unique RIVNUT fastener has recently been specified for use in the construction of roadsigns by a major European manufacturer. RIVNUT is a blind fastener so the sign ...

Staytite Technical Advice

Do you require advice about the application of fasteners? Staytite can aid with new designs or advice with developing the manufacture of an existing product, whether it is a need ...

Spiralock® Arrives At Zygology

Vibration, overloading, environmental forces and other external impacts and environmental forces can quickly result in a loss of function of bolted joints leading to costly, ...